Why (and When) Your Lawn Needs Dethatching and Overseeding

July 15, 2019

When you walk across your lawn, do you feel any spongy or “bouncy” areas under foot? Or are parts of the lawn starting to show weak or thin growth, or pale colors? This isn’t uncommon in our area, and is often a sign that your lawn needs dethatching. While many people like to get out and start raking and dethatching as soon as the snow melts in the spring, dethatching your lawn during wet seasons can cause hard-to-fix damage and not all lawns need dethatching! Here’s a quick guide to know if it’s time to dethatch and overseed your lawn.

What Is Thatch?

As old grass roots and rhizomes biodegrade, they form a dense layer of thatch. This nestlike collection of living and dead plant material forms at the base of the grass, where the stems grow into the soil. Thatch doesn’t form because you’ve left grass clippings on your lawn; in fact, as grass clippings decompose, they also help old roots and rhizomes decompose, which reduces the amount of thatch. A thin layer of thatch—less than 1/2 inch—is actually beneficial to your lawn. Not only does it act like mulch, preserving moisture and insulating plant crowns from fluctuations in temperature, but it also allows water, nutrients, and air to penetrate into the soil, where they bring nourishment to plant roots.

When decomposition on the surface of the lawn is impeded—for example, by a layer of leaves or pine needles—the thatch layer can grow thicker, sometimes up to 1 inch or more. This keeps the roots of your lawn grass from penetrating deeply into the soil. So instead of absorbing essential nutrients and fertilizer from the soil, they remain higher up in the thatch layer, where they can suffocate in heavy rains or during irrigation. In drier, hotter temperatures, the thatch-locked grass roots become stressed and can die and too much thatch can harbor insects and grass diseases.

Is It Time to Dethatch?

Dethatching will break up that thick barrier of organic matter by slicing through it into the soil. But how do you know if it’s time to dethatch your lawn?

Start by taking a test patch. Using a trowel or a small spade, outline a square or circular shape about 3 inches wide by 5 inches deep, and dig up the grass and soil. Place it on its side and measure the layer of thatch; it’s easy to spot, thanks to its yellowed, stringy appearance. If it’s 1/2 inch or less, you don’t need to dethatch.

If the thatch layer is thicker than 1/2 inch, your lawn could benefit from dethatching. You’ll want to time dethatching to peak growing times for the type of grass on your lawn. Most lawns in the Northeast have some combination of cool-season grasses, such as Kentucky bluegrass, rough bluegrass, creeping red fescue, ryegrass, or tall turf fescue. For these grasses, late summer or early fall are the best bet; because the grass is still actively growing, your lawn will recover from dethatching faster.

Dethatching can be accomplished with manual or power rakes, or with vertical mowers (verticutters) that slice below the surface, through the thatch, and into the soil. Keep in mind that manual rakes are heavy, so the process can be time-consuming. And not all lawn and garden stores rent power equipment. You’ll get more consistent, faster results by hiring a lawn-care service to do your dethatching and if the thatch layer on your lawn is more than 2 inches thick, you’ll definitely want to bring in the professionals.

When Should I Overseed?

The planting of new grass seed directly into existing turf, without completely removing the turf and reconditioning the soil, is known as overseeding. This helps fill in any bare patches caused by dethatching. It will also give your lawn a lush, vibrant green look, and will improve the density of your lawn—so no more pale, spongy spots.

Premium grass seed is the best choice for overseeding. This is especially true for older lawns, which were often established with grass varieties that are more prone to damage from insects, disease, and drought. Modern varieties of grass seed have been developed to better withstand these conditions, and often need less fertilizer, water, and pesticides to keep them looking healthy and abundant.

Before overseeding, be sure to check for underlying problems like poor or compacted soil, improper drainage, poor air circulation, low soil pH, and insufficient exposure to sunlight. These will cause even the best-quality grasses to deteriorate over time—which means more time and money to fix.

Keeping Your Lawn Healthy, Year after Year

Knowing the signs of stress that come with the buildup of thatch will allow you to stay on top of the problem—before it becomes a major headache. And if your lawn does need dethatching, be sure to do it carefully and thoroughly. You’ll ensure that your lawn remains healthy and beautiful for many years’ worth of barbecues, summer evenings around the fire pit, and backyard relaxation.

Get in touch with us today for dethatching and overseeding services. Click Here to visit Nature Works Lawn Care Page.
– Robin Catalano

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